During the fifteenth year of support, Program-project HL08682 investigators studied mechanisms of cardiovascular regulation with specific emphasis upon central, spinal and peripheral nervous control, biochemical and metabolic regulation, endotoxin shock, cardioplumonary integration, transmembrane ion transport, catecholamine metabolism, the reninangiotensin system, dynamics of the pulmonary circulation and the regulation of hibernation and arousal. The research has resulted in the description of animal models of surgically unbalanced autonomic innervation of the heart, the development of a canine model of Sick Sinus Syndrome, and the collateral flow channels in the dog with and without total cardiac denervation. A concept of glucose dyshomeostasis was examined during the presence of alpha and beta adrenergic blockade, together with the processes of glucose and RES-Insulin regulation in endotoxicosis. Neurophysiological evidence for spatial summantion in the CNS from unmyelinated afferent fibers was elicited and the influences of clonidine was studied in spinal cats. Ascending and descending cardiovascular pathways were located in the spinal cord. Renal function and plasma renin concentration after total cardiac denervation was examined in conscious dogs. Ion transport and myocardial calcium storage was studied in the circulatory shock model. The organization of central respiratory neurons was investigated under conditions of quiet breathing and during barbiturate depression. The phrenic neuronal architecture was mapped by means of horseradish peroxidase. An extensive review of the mechanical properties of arteries was published in physiological reviews; the physiological bases for differences in flow using internal mammary versus saphenous vein grafts in coronary artery bypass were determined. Progress was made in the identification of a hibernation inducing "trigger" from the plasma of hibernating woodchucks, and myocardial sympathetic activity during rewarming from severe hypothermia was examined. Studies of plumonary hemodynamic parameters during administration of sodium nitroprusside, during carotid occlusion, and during acute lung injury were reported.